Assembly methods of a sma assembly and an ois device

ABSTRACT

An assembly method of a SMA assembly, includes disposing a lens holder unit on a SMA unit, the lens holder unit being provided with a first spring, a lens holder and a coil that are mounted on the first spring, with the first spring pressed against a mounting surface of the SMA unit; and bonding the first spring of the lens holder unit with the mounting surface of the SMA unit. The assembly process is simplified, the coating and soldering space become big to facilitate the bonding process, and the joining force between the SMA unit and the lens holder unit is enhanced.

FIELD OF THE INVENTION

The present invention relates to technical field of optical imagestabilization (OIS) devices for cameras, and more particularly toassembly methods of a shape memory alloy (SMA) assembly and an OISdevice with the SMA assembly.

BACKGROUND OF THE INVENTION

With the developments of demands for compact and functional electronicproducts such as mobile phones or tablet PC with cameras, therequirements for the cameras driver become higher, especially for theoptical image stabilization.

Thus optical image stabilizer (OIS) is applied to camera lens thatrequires high quality images, to prevent the image damage caused by thehand shaking during the use of the camera. Conventional OIS devicesinclude VCM (voice coil motor) OIS devices, SMA OIS devices, VCM-SMA OISdevices, piezoelectric OIS devices, and stepper motor OIS devices, etc.The VCM-SMA OIS devices become popular due to the quick driving speed,small size, lower power and higher efficiency.

Following is the assembly process for this VCM-SMA OIS device.

First, assembling the VCM assembly in advance. Concretely, theconventional VCM assembly includes a yoke assembly and a lens holderassembly. The yoke assembly includes a yoke, a coil and four magnetslocated at four corners of the yoke, these elements are fixedtemporarily by means of UV coating. And then, the yoke assembly ismounted to the lens holder assembly which includes a bottom, a lensholder, and four spacers. Concretely, the lens holder is supported bythe bottom, and the four spacers are fixed temporarily on the bottom.During the assembly, the yoke assembly is covered on the lens holderassembly, and coating and soldering are proceeded to form the VCMassembly.

And then, the VCM assembly is mounted on a SMA unit to form the VCM-SMAOIS device.

However, the coating and soldering during the assembly process for theVCM assembly and the SMA unit are difficult, that is because coating andsoldering positions will be covered by the yoke when the yoke assemblyis covered on the lens holder assembly. Thus the element bonding for theVCM assembly must be made before it's mounted to the SMA unit, whichcauses the process complicated. During the assembly between the VCMassembly and the SMA unit, the coating and soldering space between thejoining surfaces are very small due to the yoke cover, which makes thebonding further difficult. In addition, the coating and soldering mustbe performed artificially, and the efficiency and yield are low.

Thus, there is a need for improved assembly methods of a SMA assemblyand an OIS device to overcome the drawbacks mentioned above.

SUMMARY OF THE INVENTION

One aspect of the present invention is to provide an assembly method ofa SMA assembly, thereby the assembly process is simplified, the coatingand soldering space become big to facilitate the bonding process, andthe joining force between the SMA unit and the lens holder unit isenhanced.

Another aspect of the present invention is to provide an assembly methodof an OIS device, thereby the assembly process for the SMA assembly issimplified, the coating and soldering space become big to facilitate thebonding process, and the joining force between the SMA unit and the lensholder unit is enhanced.

To achieve above objectives, an assembly method of a SMA (Shape MemoryAlloy) assembly includes step (1), disposing a lens holder unit on a SMAunit, the lens holder unit being provided with a first spring, a lensholder and a coil that are mounted on the first spring, with the firstspring pressed against a mounting surface of the SMA unit; and step (2),bonding the first spring of the lens holder unit with the mountingsurface of the SMA unit.

As a preferred embodiment, the step (2) further comprises coating gluefrom a through hole of the first spring to the mounting surface of theSMA unit, with partial mounting surface of the SMA exposed on thethrough hole.

As another preferred embodiment, the step (2) further comprises weldinga leg of the first spring with the mounting surface of the SMA unit,with the leg rested on the mounting surface.

Preferably, before the step (2) the method further includes: disposing aspacer unit on the first spring, with the spacer unit contacted with themounting surface of the SMA unit; and bonding the spacer unit with thefirst spring and the mounting surface.

Preferably, the method further comprises locating the spacer unit near athrough hole of the first spring whereby partial mounting surface of theSMA unit is exposed, said bonding the spacer unit with the first springand the mounting surface comprises coating glue on the through hole anda side of the spacer unit.

Preferably, the SMA unit includes a bottom that is mounted thereon andprovided with the mounting surface.

An assembly method of an OIS device, includes assembling a SMA assemblyaccording to steps (1) and (2) mentioned above; bonding a yoke assemblyon the SMA assembly, the yoke assembly being provided with a yoke, asecond spring and magnets accepted in the yoke; and bonding a cover uniton the yoke assembly, with the yoke assembly and the SMA assemblycovered by the cover unit.

As a preferred embodiment, the step (2) further comprises coating gluefrom a through hole of the first spring to the mounting surface of theSMA unit, with partial mounting surface of the SMA exposed on thethrough hole.

As another preferred embodiment, the step (2) further comprises weldinga leg of the first spring with the mounting surface of the SMA unit,with the leg rested on the mounting surface.

Preferably, before the step (2) the method further includes disposing aspacer unit on the first spring, with the spacer unit contacted with themounting surface of the SMA unit; and bonding the spacer unit with thefirst spring and the mounting surface.

Preferably, the method further comprises locating the spacer unit near athrough hole of the first spring whereby partial mounting surface of theSMA unit is exposed, said bonding the spacer unit with the first springand the mounting surface comprises coating glue on the through hole anda side of the spacer unit.

Preferably, the SMA unit includes a bottom that is mounted thereon andprovided with the mounting surface.

In comparison with the prior art, during the assembly method of the SMAassembly, the coating position and the soldering position are exposedoutside, without covered by additional elements such as a yoke of a VCM,thus the coating and soldering space are big, which facilitates thebonding process to improve assembly efficiency. Furthermore, the coatingprocess can be done after the lens holder unit is assembled with the SMAunit, thus the joining force therebetween is enhanced. In addition,because the first spring of the lens holder unit can be directly mountedon the mounting surface of the SMA unit, thus a bottom can be reduced bycomparison with the conventional structure, which simplifies thestructures of SMA assembly and the OIS device.

Other aspects, features, and advantages of this invention will becomeapparent from the following detailed description when taken inconjunction with the accompanying drawings, which are a part of thisdisclosure and which illustrate, by way of example, principles of thisinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings facilitate an understanding of the variousembodiments of this invention. In such drawings:

FIG. 1 is a perspective view of a SMA assembly according to a firstembodiment of the present invention;

FIG. 2 is an exploded perspective view of FIG. 1;

FIG. 3 shows an assembly process of the SMA assembly;

FIGS. 4a and 4b shows the coating position between the SMA unit and thelens holder unit;

FIGS. 5a and 5b show the soldering position between the SMA unit and thelens holder unit;

FIG. 6 shows an assembly process of an IOS device according to oneembodiment of the present invention; and

FIG. 7 is an exploded perspective view of a SMA assembly according to asecond embodiment of the present invention.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS

Various preferred embodiments of the invention will now be describedwith reference to the figures, wherein like reference numerals designatesimilar parts throughout the various views. As indicated above, theinvention is directed to assembly methods for a SMA assembly and an OISdevice, thereby the assembly process for the SMA assembly is simplified,the coating and soldering space become big to facilitate the bondingprocess, and the joining force between the SMA unit and the lens holderunit is enhanced.

Referring to FIGS. 1 and 2, a SMA assembly 200 according to a firstembodiment of the present invention includes a SMA unit 210, a bottom220, a lens holder unit 230 and a spacer unit 240, each of whichprovides a coaxial center hole. Specifically, the SMA unit 210 made ofshape memory alloy includes a main body 211 and a mounting surface 212.The bottom 220 is mounted on the mounting surface 212 of the SMA unit210 for supporting the lens holder unit 230. It should be noted that,the bottom 220 is optional and can be omitted in other embodiments. Thedetailed structures of the SMA unit 210 are well known the personsskilled in the art, thus are omitted here. The lens holder unit 230includes a lens holder 231 for holding lens, such as lens barrel, focuslens or zoom lens, etc. therein, a coil 232 winding around the lensholder 231, and a first spring 233 for supporting the lens holder 231and the coil 232 and protecting the lens barrel, etc.

Following is the assembly process for this SMA assembly 200 according tothe present embodiment.

First, mounting the bottom 220 on the SMA unit 210. Specifically, thebottom 220 is disposed on the mounting surface 212 of the SMA unit 210,and is joined by means of coating glue, for example, so that the bottom220 can be joined temporarily.

Second, mounting the lens holder unit 230 on the SMA unit 210.Specifically, the lens holder unit 230 is assembled in advance,according to the common process, and then the lens holder unit 230 isdisposed on the bottom 220, and alignment is made. Preferably, in theassembly process of the lens holder unit 230, a spacer unit 240 can beassembled for enhancing the structure stability between the first spring233 and the bottom 220. Specifically, the spacer unit 240 is supportedby the hollowed first spring 233, with the spacer unit 240 is contactedwith the bottom 220 when the lens holder unit 230 is placed on thebottom 220. Specifically, the first spring 233 of the lens holder unit230 is pressed against the surface of the bottom 220, and a through hole233 a of the first spring 233 is aligned with a through hole 220 a ofthe bottom 220. After that, the bonding process between the lens holderunit 230 and the bottom 220 with the SMA unit 210 is made.

More specifically, the bonding process includes coating and soldering.In the coating process, glue is coated along the through holes 233 a and220 a. Partial mounting surface 212 of the SMA unit 210 is exposed, dueto the through holes 233 a and 220 a. Therefore, coating in the throughholes 233 a, 220 a can realize the bonding among the first spring 233,the bottom 220 and the SMA unit 210. FIGS. 4a and 4b shows the coatingposition. More preferably, the spacer unit is located near the throughhole 233 a. The coating process includes coating glue in the throughhole 233 a and the on a side of the spacer unit 240. In other words,glue coated in the coating position (the through hole 233 a and the sideof the spacer unit 240) will be spread on the first spring 233, thebottom 220, the SMA unit 210 and the spacer unit 240.

In the soldering process, the soldering is proceeded between a leg 233 bof the first spring 233 and the bottom 220 of the SMA unit 210, forachieving a firm connection. Preferably, the leg 233 b of the firstspring 233 is rested on the surface of the bottom 220. Since noadditional element is covered on the lens holder unit, thus solderingbetween the first spring and the bottom 220 is easy. FIGS. 5a and 5bshow the soldering position.

By this token, the coating position and the soldering position areexposed outside, without covered by additional elements such as a yokeof a VCM, thus the coating and soldering space are big, whichfacilitates the bonding process to improve assembly efficiency.Furthermore, the coating process can be done after the lens holder unit230 is assembled with the SMA unit 210, thus the joining forcetherebetween is enhanced. In addition, because the first spring 233 ofthe lens holder unit 230 can be directly mounted on the mounting surface233 a of the SMA unit, thus the bottom can be reduced by comparison withthe conventional structure, which simplifies the structures of SMAassembly and the OIS device.

The SMA assembly 200 can be assembled with a yoke assembly 310 and acover unit 320 to form an IOS device 1. Following is the assemblyprocess.

As shown in FIG. 6, concretely, the yoke assembly 310 includes magnets(not shown), a coil (not shown) and a yoke 311 covering the magnets andthe coil. The magnets are disposed at corners of the yoke, and the coilis disposed beside the magnets, these elements are assembled to form theyoke assembly. And then, the yoke assembly is bonded to the SMA assemblyby means of UV soldering, and a cover unit 320 is bonded to the yokeassembly by means of coating and UV soldering for example, to form anIOS device. It should be noted, the assembly methods for the yokeassembly 310 and the cover unit 320 can apply the conventional methods,and the more detailed descriptions are omitted here.

As another embodiment, as shown in FIG. 7, for reducing the totalthickness of the OIS device, the bottom between the SMA unit 210 and thelens holder unit 230 is removed, thus the lens holder unit 230 ismounted on the mounting surface 212 of the SMA unit 210 by mean of aninsulating layer 250 sandwiched therebetween. Under this condition, thespacer unit may be canceled. The assembly processes of the SMA assemblyand the OIS device with these configuration changes are similar to thefirst embodiment, and the coating position and the soldering positionare exposed outside, without covered by the yoke 311, thus the coatingand soldering space are big, which facilitates the bonding process toimprove assembly efficiency. Furthermore, the coating process can bedone after the lens holder unit 230 is assembled with the SMA unit 210,thus the joining force therebetween is enhanced.

While the invention has been described in connection with what arepresently considered to be the most practical and preferred embodiments,it is to be understood that the invention is not to be limited to thedisclosed embodiments, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the invention.

1. An assembly method of an SMA (Shape Memory Alloy) assembly,comprising: step (1), disposing a lens holder unit on an SMA unit, thelens holder unit being provided with a first spring, a lens holder and acoil, the lens holder and the coil being mounted on the first spring,the first spring being pressed against a mounting surface of the SMAunit; and step (2), bonding the first spring of the lens holder unitwith the mounting surface of the SMA unit, and coating glue from athrough hole of the first spring to the mounting surface of the SMAunit, at least a part of the mounting surface of the SMA being exposedon the through hole.
 2. (canceled)
 3. The assembly method according toclaim 1, wherein the step (2) further comprises welding a leg extendingfrom the first spring with the mounting surface of the SMA unit, the legbeing rested on the mounting surface.
 4. The assembly method accordingto claim 1, before the step (2) further comprising: disposing a spacerunit on the first spring, the spacer unit contacting with the mountingsurface of the SMA unit; and bonding the spacer unit with the firstspring and the mounting surface.
 5. The assembly method according toclaim 4, further comprising locating the spacer unit near a through holeof the first spring whereby at least a part of the mounting surface ofthe SMA unit is exposed, said bonding the spacer unit with the firstspring and the mounting surface comprising coating glue on the throughhole and a side of the spacer unit.
 6. The assembly method according toclaim 1, wherein the SMA unit includes a bottom that is mounted thereonand provided with the mounting surface.
 7. An assembly method of an OIS(Optical Image Stabilizer) device, comprising: assembling an SMAassembly according to steps (1) and (2) in claim 1; step (3), bonding ayoke assembly on the SMA assembly, the yoke assembly being provided witha yoke, a second spring and magnets being received in the yoke; and step(4), bonding a cover unit on the yoke assembly, the yoke assembly andthe SMA assembly being covered by the cover unit.
 8. (canceled)
 9. Theassembly method according to claim 7, wherein the step (2) furthercomprises welding a leg extending from the first spring with themounting surface of the SMA unit, the leg resting on the mountingsurface.
 10. The assembly method according to claim 7, before the step(2) further comprising: disposing a spacer unit on the first spring, thespacer unit contacting with the mounting surface of the SMA unit; andbonding the pacer assembly with the first spring and the mountingsurface.
 11. The assembly method according to claim 10, furthercomprising locating the spacer unit near a through hole of the firstspring whereby at least a part of the mounting surface of the SMA unitis exposed, said bonding the pacer assembly with the first spring andthe mounting surface comprises coating glue on the through hole and aside of the spacer unit.
 12. The assembly method according to claim 7,wherein the SMA unit includes a bottom that is mounted thereon andprovided with the mounting surface.